1. Field of the Invention
This invention relates to a waterproof structure of an antenna used favorably for GPS (global positioning system) receiving antennas that are mounted on the outdoor of moving objects such as ships and automobiles.
2. Description of the Related Art
The conventional waterproof structure of an antenna will be described with reference to FIG. 10 to FIG. 13. A first case 51 comprising a mold product consisting of synthetic resin that is served as an under case is provided with a flat plate bottom wall 51a, two ring projection walls 51b that are different in diameter and project upward from the bottom wall 51a, a circular ring recess 51c formed between the two projection walls 51b, and a pair of first notches 51d formed on the two projection walls 51b so as to be positioned opposingly each other with interposition of the recess 51c. 
Furthermore, the first case 51 comprises an arc recess holder 51e formed at the position so as to oppose to the first notch 51d, a plurality of mounting holes 51f formed on the bottom wall 51a, and a recess container 51g positioned at the center of the projection walls 51b. 
An adhesive 52 is filled in the recess 51c and contained in the recess 51c. 
An antenna 53 comprises an antenna body 54 and a coaxial cable 58, and the antenna body 54 comprises a rectangular parallelepiped antenna 55, a printed board 56 having a wiring pattern (not shown in the drawing) for attaching the antenna 55, and a box shield member 57 formed of a metal plate mounted on the printed board 56.
Furthermore, the circular cable 58 comprises a sheath 60 for sheathing a core wire 59 consisting of insulating material such as rubber, and a winding 61 that is wound partially on the sheath 60 consisting of insulating material, and the core wire 59 of the cable 58 is connected to the wiring pattern of the printed board 56 by means of soldering.
The antenna body 54 of the antenna 53 having the structure as described hereinabove is contained in the container 51g, the cable 58 is placed in the first notch 51d so as to cross the recess 51c, and the winding 61 is positioned on the holder 51e. 
The width of the first notch 51d is formed so as to be approximately equal to the diameter of the cable 58. As the result, when the cable 58 is inserted into the first notch 51d, the sheath 60 of the cable 58 is inserted into with pressure and tightly compressed on the inside of the first notch 51d and the sheath 60 of the cable 58 is in tight contact with the bottom of the first notch 51d. 
Furthermore, when the cable 58 has inserted with pressure into the first notch 51d, the bottom of the cable 58 is positioned in the adhesive 52 contained in the recess 51c, and around the bottom half of the cable 58, the space between the first notch 51d and the cable 58 is sealed with the adhesive 52 and the bottom half of the cable 58 is sealed by pressing the sheath 60 of the cable 58 with pressure on the inside wall of the first notch 51d. Thereby, the container 51g is sealed on the lead-out side of the cable 58 of the first case 51 side.
A second case 62 comprising a mold product consisting of synthetic resin that is served as a upper case comprises a bowl-shaped top wall 62a having the same peripheral configuration as that of the bottom wall 51a, a circular ring projection 62b that projects downward from the top wall 62a, a second notch 62c formed on the projection 62b having the same width as that of the first notch 51d that is positioned so as to oppose to the first notch 51d, a circular recess holder 62d formed at the position so as to oppose to the second notch 62c, a plurality of mounting holes 62e formed on the top wall 62a at the positions opposing to the mounting holes 51f, and a recess container 62f positioned at the center of the projection 62b. 
The second case 62 is fitted combinedly to the first case 51 so as to cover over the antenna body 54, and a plurality of screws 63 are inserted and screwed from the mounting holes 51f side of the first case 51 into the mounting holes 62e of the second case 62 to thereby combine the first case 51 to the second case 62.
When the first and second cases 51 and 62 are combined, the winding 61 of the sheath 60 of the cable 58 is held with the holders 51e and 62d, the projection 62b is inserted into the recess 51c, and the top end of the projection 62b is embedded into the adhesive 52.
Furthermore, at that time, the cable 58 is positioned in the second notch 62c, the top of the second notch 62c presses the sheath 60 onto the first notch 51d side, the sheath 60 is inserted with pressure into and tightly pressed on the inside wall of the second notch 62. Thereby, the container 62f is sealed on the lead-out side of the cable 58 of the second case 62 side.
In other words, on the lead-out side of the cable 58 of the first and second cases 51 and 62, by inserting with pressure into and tightly pressing the cable 58 on the first and second notches 51d and 62c, the containers 51g and 62f are sealed, and by embedding the projection 62b in the adhesive 52, the surrounding of the container 51g and 62f is sealed. As the result, the antenna body 54 is waterproofed.
Next, a method for combining the first and second cases 51 and 62 will be described with reference to FIG. 13. As shown in FIG. 13, the second case 62 covers the first case 51 so that the second notch 62c is fitted to the cable 58 in the state that the cable 58 has been inserted with pressure into the first notch 51d of the first case 51.
As the result, at first, the inside wall that is opposing to the second notch 62c is brought into contact with the sheath 60, and when the second case 62 is moved downward further in this state, the top end of the projection 62b is embedded in the adhesive 52.
The surface of the adhesive 52 moves upward concomitantly with embedding of the projection 62b, the top of the second notch 62c presses the sheath 60 of the cable 58, the sheath 60 is pressed on the bottom of the first notch 51d, and the combination of the first and second cases 51 and 62 is completed.
However, though the surface of the adhesive 52 moves upward concomitantly with embedding of the projection 62b when these cases 51 and 62 are combined, because the width of the second notch 62c is formed so as to be approximately equal to the diameter of the cable 58, there is no space between the second notch 62c and the top open portion of the cable 58. As the result, the adhesive 52 does not penetrate into the space between the second notch 62c and the cable 58 though the surface of the adhesive moves upward, and no penetration of the adhesive 52 results in poor sealing between the second notch 62c and the cable 58 and the results in poor waterproofing of the containers 51g and 62f. 
In particular, variation of contact tightness between the second notch 62c and the cable 52 due to variation of the width of the second notch 62c caused when the second case 62 is fabricated or variation of the diameter of the cable 58 or a slight space between the second notch 62c and the cable 52 results in poor sealing and further results in poor waterproof of the containers 51g and 62f. 
There is no space between the second notch 62c and the open end top of the cable 58 because the width of the second notch 62c is formed so as to be approximately equal to the diameter of the cable 58 in the case of the waterproof structure of the conventional antenna. As the result, the adhesive 52 does not penetrate into the space between the second notch 62c and the cable 58, and no penetration of the adhesive 52 results in poor sealing between the second notch 62c and the cable 58 and results in poor waterproofing of the containers 51g and 62f. 
In particular, variation of contact tightness between the second notch 62c and the cable 52 due to variation of the width of the second notch 62c caused when the second case 62 is fabricated or variation of the diameter of the cable 58 or a slight space between the second notch 62c and the cable 52 results in poor sealing and further results in poor waterproofing of the containers 51g and 62f. The poor waterproofing causes a problem.
In view of the above, the object of the present invention is to provide an inexpensive reliable waterproof structure of an antenna.
To solve the abovementioned problem, the first solution means has the structure provided with first and second cases, an antenna body contained in containers comprising the first and second cases, and a cable that is lead to the outside of the first and second cases, wherein the first cases has a recess for containing adhesive and a first notch for placing the cable that is disposed so as to cross the recess, the second case has a projection that projects into the recess and a second notch disposed on the projection that is positioned so as to oppose to the first notch for positioning the cable, a width of an open end top of the second notch is formed so as to be wider than a diameter of the cable, the cable that crosses the recess is placed in the first notch, and the projection that projects into the recess allows the adhesive to penetrate into the second notch to thereby seal a space between the cable and the second notch and to thereby seal the containers.
The second solution means has the structure in which a width of the first notch is formed so as to be approximately equal to the diameter of the cable.
Furthermore, the third solution means has the structure in which the recess is formed in ring-shape, the projection is formed in ring-shape, a top end of the projection excepting a portion positioned at the second notch is embedded in the adhesive and the containers are sealed thereby.
Furthermore, the fourth solution means has the structure in which the cable is positioned at a top of the second notch, and the space between the second notch including the top and the cable is sealed with the adhesive.
Furthermore, the fifth solution means has the structure in which the second notch is provided with an inclination formed so that a width of the second notch becomes wider from the top toward the open end top.